There's a cave in Vietnam which has been newly opened to tourism called Hang Sơn Đoòng (English Wikipedia article here).
My question is about the syllable in the name of the cave which is represented as đoòng
. I didn't think the orthography allowed a nucleus written as oo
, but it's there in the Vietnamese version of the page as well.
Also, the only matches for đoòng
that I can find are references to the cave. Is this a possible nucleus in Vietnamese orthography, and if so, what does it represent?